ABSTRACT
Objective To establish a new kinetic spectrophotometry for determination of formaldehyde in water sample. Methods Micro formaldehyde could sensitively catalyze the discoloring reaction of methyl orange oxidized by potassium bromated in dilute H3PO4 medium, the relationship between the reaction speed and the content of formaldehyde could be determinated by spectrophotometry, then the content of formaldehyde could be determinated. Results The optimum condition and kinetic paramneters were investigated and showed in the present paper in detail. The calibration curve showed linearity in the range of 0.13-3.0 ?g/ml and the limit of detection was 4.7?10-5 mg/ml. The RSDs ranged from 1.5% to 3.3%.The recovery rates ranged from 97.3% to 102.0%. Conclusion The mothed was simple, rapid and more sensitive, can be used for the determination of micro amounts of formaldehyde in water sample with satisfied results.
ABSTRACT
Objective To establish a new spectrophotometry for determination of trace resorcin. Methods Resorcin can inhibit discolouring reaction of bromophenol red induced by H2O2 ,which is catalyzed by Fe(Ⅲ) in NH3-NH4Cl medium. Results The detection limit of this method was 0.054 ?g/ml, linear range was 0.16-2.6 ?g/ml, the optimum reaction temperature was 75℃ and the optimum reaction time was 4 min. Conclusion The present method is simple, accurate and can be used to determine trace resorcin in waste water.
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Objective To establish a discoloring kinetic analysis method for determination of trace formaldehyde in textiles. Methods Based on the catalysis of formaldehyde on the discoloring reaction of bromophenol blue oxidized by potassium bromated in phosphoric acid medium,the contents of formaldehyde in textiles were determinated by spectrophotometry. The optimum condition and kinetic parammeters of the reaction were studied in detail. Results The optimum required volumes of reagents were 2.0,3.0,1.0 ml for H3PO4,KBrO3 and bromophenol blue respectively.The reaction was optimized at 85 ℃ for10 min.At working wave length of 430 nm,the linear range was 0.05-0.40 ?g/ml,the detection limit was 0.006 9 ?g/ml ,the recovery rate and RSD were 96%-106% and 2.9%-3.2% respectively. Conclusion This method was easy ,rapid and sensitive for the determination of trace formaldehyde in textiles.
ABSTRACT
Objective To establish a kinetic spectrophotometric method for the determination of trace catechol in the waste water. Methods Trace catechol can sensitively inhibit the Arsenazo decolorization reaction with H2O2 catalyzed by Cu(Ⅱ)in dilute H2SO4 medium. Based on the changing of catalyzed reaction speed, a new inhibitory kinetic spectrophotometric method for the determination of trace catechol in the waste water was established. Results The optimum condition, kinetic parameters and reaction mechanism were investigated. It is shown that the linear range of determination was 0.2-1.8 mg/ L, the detection limit was 0.084 mg/L. The RSDs of ?A for 0.6 mg/L,1.12 mg/L and 1.6 mg/L catechol standard materials for 11 parallel determination were 2.4%, 1.2% and 1.6% respectively. The recovery rates were 98.0% and 96.0%. Conclusion This method can be used for determination of trace catechol in waste water with satisfactory results.
ABSTRACT
Objective To establish an easy, rapid and sensitive method for determination of micro 2,4-dinitrotoluene in waste water. Methods Based on the fact that micro 2,4-dinitrotoluene could inhibit the discoloring oxidation reaction of methylene blue by KIO4 in the HC1 solution, micro 2,4-dinitrotoluene was determined using kinetic spectrophotometric method. Results A new kinetic spectrophotometric method for determination of micro 2,4-dinitrotoluene was established. The linear range of the method was 0.20?10~(-5)-1.8?10~(-5) mg/L, the detection limit was 1.7xlO'7 mg/L. When the method was applied to the determination of the 2,4-dinitrotoluene in waste water, its recovery rates in standard addition method were 95.6%-99.1% and the RSDs were 1.5%-2.6%. Conclusion The method was easier to operate and more rapid, which was suitable for the determination of micro 2,4-dinitrtoluene in wastewater.